Grounding digital output

[mullenc525]

On a 6211, will I cause any damage by grounding one of the digital out signals and then telling the DAQ to switch that channel on? I understand the D/O can only supply 16mA. I expect the supply voltage will simply fall such that there is no overcurrent, but am not sure.

Thanks

[AnalogKid2DigitalMan]

Even though the outputs are protected, it does not sound advisable to do so. From the user's manual:

I/O Protection

Each DI, DO, and PFI signal is protected against overvoltage,

undervoltage, and overcurrent conditions as well as ESD events. However,

you should avoid these fault conditions by following these guidelines.

• Do

not connect a DO or PFI output lines to any external signal source,

ground signal, or power supply.

• Understand the current requirements of the load connected to DO or

PFI output signals. Do not exceed the specified current output limits

of the DAQ device. NI has several signal conditioning solutions for

digital applications requiring high current drive.

• Do

not drive a DI or PFI input line with voltages outside of its normal

operating range. The PFI or DI lines have a smaller operating range

than the AI signals.

Increasing Current Drive

The total internal current limit for digital outputs and power down from the

+5 V terminals is 50 mA. You can increase this internal current limit by

supplying an external +5 V supply. Refer to the

+5 V Power as an Input

section of Chapter 3,

Connector Information.

Here's a link to the manual:

https://www.ni.com/docs/en-US/bundle/usb-621x-manual/resource/usb-621x-manual.pdf